EGYPTIANS have begun casting their ballots in the country's first free vote for a leader in 5,000 years of history.

Polls opened at 8am local time (7am BST) with five candidates from a list of 13 reckoned by polls and analysts to have any chance of success in the quest to replace Hosni Mubarak, who was deposed last year in the Tahrir Square revolution.

The military council that has taken supreme power in the interim last night tried to allay fears it would rig the elections in favour of its preferred candidates, insisting it would not allow any "violations".

A sudden surge in support in government-sponsored polls for Ahmed Shafiq, a former Air Force general who was Mr Mubarak's last prime minister, has led to widespread rumours that the ruling Supreme Council of the Armed Forces is plotting to put a new "front man" in power.

But a spokesman, Mohammed al-Assar, issued a statement through the state news agency saying: "The participation of citizens in the presidential election is the best guarantee of the transparency and security of the electoral process.

"We will not allow any violation or attempt to influence the electoral process or the voters."

It also belatedly granted papers to allow some international election monitors, including the US-based Carter Centre, access to polling stations.

Assuming no candidate wins an outright 50 per cent majority after the vote on Wednesday and Thursday, the leading two will, in the style of the French presidential elections, go through to a second round next month.

The novelty of the vote and lack of trust in the opinion polls mean few are daring to predict the outcome.

Long queues formed from early in the morning at the country's 13,000 polling booths, which will stay open until 8pm. "I can die in a matter of months, so I came for my children, so they can live," Medhat Ibrahim, who suffers from cancer, said as he waited in a poor district south of Cairo. "We want to live better, like human beings."

The front-runner, ever since Mr Mubarak's fall after 18 days of dramatic protests in Tahrir Square, has been Amr Moussa, a former foreign minister and secretary-general of the Arab League.

But as a member of the wealthy ruling elite, and the oldest candidate at 75, he comes over as out-of-touch to many working class and younger voters, empowered for the first time.

Although they are trailing in such polls as there have been, few rule out the possibility of at least one, and possibly two Islamists making through this round. The polls greatly underestimated their likely support in parliamentary elections in December and January, in which the Muslim Brotherhood and the even more conservative Salafi movement won almost three-quarters of the seats.

If the Brotherhood were able to repeat that success, the winner would be Mohammed Morsi, an American-educated professor of engineering, with conservative views on social issues but a staunchly free market economic agenda.

He has been strongly challeged by Abdulmoneim Aboul Fotouh, a former Brotherhood leader who left the movement after his attempts to reform it failed, and who has publicly committed himself to respect personal freedoms and a multi-party democracy.

The fifth candidate, Hamdeen Sabahi, has had a late surge in popularity. His socialist and nationalist beliefs hark back to the 1950s and 60s, but still have an appeal, especially for the urban liberals who fought to bring down the military regime but regard Islamic rule as almost as bad.

Even many of the people who took no part in the revolution - a "silent majority" known popularly as the Hizb al-Kanaba, or Sofa Party – are positive about the outcome of the election. An opinion poll said 52 per cent of people were "optimistic about the future", compared to just 18 per cent who were pessimistic.

Ahmed Saber, 44, a doctor, said the Muslim Brotherhood's "Renaissance Project" could turn Egypt into an advanced country in 20 years. "Look what the Islamist party has done in Turkey," he said - a common comparison, though the Brotherhood itself rejects it. "We want to do the same."

But some are sceptical that after so many years in power the military and their now dissolved front party, the National Democratic Party, are prepared really to hand over power.

"We aren't used to fair elections," said Mohammed Ali, 46, an IT engineer walking across Tahrir Square. "The NDP consider this their last battle, and they will use all the means they have planned and practised to fix the election."

He claimed, as have others, that old regime officials have been buying identity cards and voting papers.